2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 3: Oye Intl. Symp. / Ionic Liquid and Aluminum
| Editors: | Kongoli F, Feng N, Polyakov P, Gaune-Escard M |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2016 |
| Pages: | 180 pages |
| ISBN: | 978-1-987820-40-9 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Control of dispersoids in 7475 aluminum alloy
Yiran Zhou1; Lei Kang2; Gang Zhao3; Ni Tian2;1, shenyang, China; 2NORTHEASTERN UNIVERSITY, Shenyang, China; 3, Shenyang, China;
Type of Paper: Regular
Id Paper: 297
Topic: 37
Abstract:
The characteristic of dispersoids in the semi-continuous casting ingot of 7475 aluminum alloy and the evolution of their distribution during rolling have been investigated by means of optical microscopy (OM) and transmission electron microscopy (TEM). The size, shape and distribution of dispersoids are controlled by pre-treatment before homogenization of semi-continuous casting ingot of 7475 aluminum alloy. The results show that there are many coarse triangular, irregular block and spindly rod-like dispersoids which contain some of Cr and Mg and a little of Cu and Zn in the 7475 aluminum alloy which subject to conventional one-step homogenization treatment at 470¡æ for 24h. The size and the distribution of the Cr-containing dispersoids is not uniform. The width of the coarse dispersoids is close to 1 um and the length of the spindly rod-like dispersoids is more than 4 um. There is no dispersoids in the center of the dendritic grains, but the nonuniform distribution of dispersoids is completely eliminated when the hot rolling reduction exceed 80%. The dispersoids in the semi-continuous casting ingot of 7475 aluminum alloy can be significantly refined and homogenously distributed by pre-treated at 240¡æ~340¡æ before the conventional one-step homogenized at 470¡æ for 24h. The pre-treatment can stimulate the nucleation of Cr-containing dispersoids, increase their density and narrow down the dispersoids free zone. The size of the dispersiods in semi-continuous casting ingot of 7475 aluminum alloy ingot is dramatically reduced by pre-treated at 240 ¡æ for 48h before the conventional homogenization at 470¡æ for 24h, and the width of the coarse dispersoids and length of the spindly rod-like ones are less than 0.3 um and 1 um, respectively, so that the dispersiods are hardly observed in the etched sample by OM.
Keywords:
dispersoids;7475 aluminum alloy;homogenization;pre-treatment;Al18Mg3Cr2 phaseReferences:
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